mirror of https://github.com/wb2osz/direwolf.git
127 lines
3.8 KiB
C
127 lines
3.8 KiB
C
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/*------------------------------------------------------------------
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*
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* Module: strlcat.c
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*
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* Purpose: Safe string functions to guard against buffer overflow.
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*
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* Description: The size of character strings, especially when coming from the
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* outside, can sometimes exceed a fixed size storage area.
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*
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* There was one case where a MIC-E format packet had an enormous
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* comment that exceeded an internal buffer of 256 characters,
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* resulting in a crash.
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*
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* We are not always meticulous about checking sizes to avoid overflow.
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* Use of these functions, instead of strcpy and strcat, should
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* help avoid issues.
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*
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* Orgin: From OpenBSD as the copyright notice indicates.
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* The GNU folks didn't think it was appropriate for inclusion
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* in glibc. https://lwn.net/Articles/507319/
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*
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* Modifications: Added extra debug output when strings are truncated.
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* Not sure if I will leave this in the release version
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* or just let it happen silently.
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*
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*---------------------------------------------------------------*/
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#include <stdlib.h>
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#include <string.h>
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#include "direwolf.h"
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#include "textcolor.h"
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/* $NetBSD: strlcat.c,v 1.5 2014/10/31 18:59:32 spz Exp $ */
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/* from NetBSD: strlcat.c,v 1.16 2003/10/27 00:12:42 lukem Exp */
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/* from OpenBSD: strlcat.c,v 1.10 2003/04/12 21:56:39 millert Exp */
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/*
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* Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND TODD C. MILLER DISCLAIMS ALL
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* WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
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* FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Appends src to string dst of size siz (unlike strncat, siz is the
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* full size of dst, not space left). At most siz-1 characters
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* will be copied. Always NUL terminates (unless siz <= strlen(dst)).
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* Returns strlen(src) + MIN(siz, strlen(initial dst)).
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* If retval >= siz, truncation occurred.
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*/
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#if DEBUG_STRL
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size_t strlcat_debug(char *__restrict__ dst, const char *__restrict__ src, size_t siz, const char *file, const char *func, int line)
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#else
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size_t strlcat_debug(char *__restrict__ dst, const char *__restrict__ src, size_t siz)
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#endif
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{
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char *d = dst;
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const char *s = src;
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size_t n = siz;
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size_t dlen;
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size_t retval;
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#if DEBUG_STRL
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if (dst == NULL) {
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text_color_set (DW_COLOR_ERROR);
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dw_printf ("ERROR: strlcat dst is NULL. (%s %s %d)\n", file, func, line);
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return (0);
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}
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if (src == NULL) {
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text_color_set (DW_COLOR_ERROR);
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dw_printf ("ERROR: strlcat src is NULL. (%s %s %d)\n", file, func, line);
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return (0);
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}
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if (siz == 1 || siz == 4) {
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text_color_set (DW_COLOR_ERROR);
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dw_printf ("Suspicious strlcat siz. Is it using sizeof a pointer variable? (%s %s %d)\n", file, func, line);
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}
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#endif
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/* Find the end of dst and adjust bytes left but don't go past end */
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while (n-- != 0 && *d != '\0')
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d++;
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dlen = d - dst;
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n = siz - dlen;
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if (n == 0) {
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retval = dlen + strlen(s);
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goto the_end;
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}
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while (*s != '\0') {
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if (n != 1) {
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*d++ = *s;
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n--;
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}
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s++;
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}
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*d = '\0';
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retval = dlen + (s - src); /* count does not include NUL */
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the_end:
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#if DEBUG_STRL
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if (retval >= siz) {
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text_color_set (DW_COLOR_ERROR);
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dw_printf ("WARNING: strlcat result length %d exceeds maximum length %d. (%s %s %d)\n",
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(int)retval, (int)(siz-1), file, func, line);
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}
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#endif
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return (retval);
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} |